s 

cop  20 


, 


Pterin        J.    Men  Art*?. 


STATE  OF  ILLINOIS 
DEPARTMENT  OF  REGISTRATION  AND  EDUCATION 

DIVISION  OF  THE 

STATE  GEOLOGICAL  SURVEY 

FRANK  W.  DE  WOLF,  Chief 


Cooperative  Goal  Mining  Series 

BULLETIN  20 


CARBONIZATION  OF  ILLINOIS 
COALS 

IN 

INCLINED  GAS  RETORTS 


F.  K.  OVITZ 
U.  S.  Bureau  of  Mines 

(Preliminary  to  an  enlarged  report  by  the  Bureau  of  Mines) 


ILLINOIS  COAL  MINING  INVESTIGATIONS 

Prepared  under  a  cooperative  agreement  between  the  Illinois  State  Geological  Survey 

Division,  the  Engineering  Experiment  Station  of  the  University  of  Illinois, 

and  the  U.  S.  Bureau  of  Mines. 


PRINTED  BY  AUTHORITY  OF  THE  STATE  OF  ILLINOIS 


URBANA,  ILLINOIS 
1918 


^LtwoitrocorDGTew: 


SURVEY  LIBRARY 
WA»   12  ,^60 


The  Forty-seventh  General  Assembly  of  the  State  of  Illinois, 
with  a  view  of  conserving  the  lives  of  the  mine  workers  and  the 
mineral  resources  of  the  State,  authorized  an  investigation  of  the 
coal  resources  and  mining  practices  of  Illinois  by  the  Department 
of  Mining  Engineering  of  the  University  of  Illinois  and  the  State 
Geological  Survey  Division  in  cooperation  with  the  United  States 
Bureau  of  Mines.  A  cooperative  agreement  was  approved  by  the 
Secretary  of  the  Interior  and  by  representatives  of  the  State  of 
Illinois. 

The  direction  of  this  investigation  is  vested  in  the  Director 
of  the  United  States  Bureau  of  Mines,  the  Chief  of  the  State  Geo- 
logical Survey  Division,  and  the  Director,  Engineering  Experi- 
ment Station,  University  of  Illinois,  who  jointly  determined  the 
methods  to  be  employed  in  the  conduct  of  the  work  and  exercise 
general  editorial  supervision  over  the  publication  of  the  results, 
but  each  party  to  the  agreement  directs  the  work  of  its  agents  in 
ving  on  the  investigation  thus  mutually  agreed  on. 

e  reports  of  the  investigation  are  issued  in  the  form  of 

either  by  the  State  Geological  Survey  Division,  the  En- 

Nperiment  Station,  University  of  Illinois,  or  the  Uni- 

°.au  of  Mines.  For  copies  of  the  bulletins  issued  by 

ical  Survey  Division,  address  State  Geological 

N*bana,  Illinois ;  for  those  issued  by  the  Engi- 

^ss  Engineering  Station,  University  of  Illi- 

id  for  those  issued  by  the  U.  S.  Bureau 

U.  S.  Bureau  of  Mines,  Washington, 


3  3051  00006  4075 


Digitized  by  the  Internet  Archive 

in  2012  with  funding  from 

University  of  Illinois  Urbana-Champaign 


http://archive.org/details/carbonizationofi20ovit 


STATE  OF  ILLINOIS 
DEPARTMENT  OF  REGISTRATION  AND  EDUCATION 

DIVISION  OF  THE 

STATE  GEOLOGICAL  SURVEY 

FRANK  W.  DE  WOLF,  Chief 


Cooperative  Coal  Mining  Series 

BULLETIN  20 


CARBONIZATION  OF  ILLINOIS 
COALS 

IN 

INCLINED  GAS  RETORTS 


F.  K.  OVITZ 

U.  S.  Bureau  of  Mines 

(Preliminary  to  an  enlarged  report  by  the  Bureau  of  Mines) 


ILLINOIS  COAL  MINING   INVESTIGATIONS 

Prepared  under  a  cooperative  agreement  between  the  Illinois  State  Geological  Survey 

Division,  the  Engineering  Experiment  Station  of  the  University  of  Illinois, 

and  the  U.  S.  Bureau  of  Mines. 


PRINTED   BY   AUTHORITY   OK  THE   STATE   OF   ILLINOIS 


URBANA,  ILLINOIS 
1918 


STATE  OF  ILLINOIS 
DEPARTMENT  OF  REGISTRATION  AND  EDUGATION 

DIVISION  OF  THE 

STATE  GEOLOGICAL  SURVEY 

Frank  W.  DeWolf,  Chief 


Committee  of  the  Board  of  Natural  Resources 
and  Conservation 

Francis  W.  Shepardson,  Chairman 

Director  of  Registration  and  Education 

David  Kinley 

Representing  the  President  of  the  Uni- 
versity of  Illinois 


Thomas  C.  Chamberlin 
Geologist 


CONTENTS 


PAGE 

Introduction     7 

Object  of  tests 7 

Summary  of  results  and  conclusions 8 

Acknowledgments  9 

Description  of  tests 9 

Coal  used 10 

Retorts   10 

Measurement  of  temperatures 11 

Mixing  and  sampling  coal 11 

Weighing  the  coal 12 

Handling  and  sampling  coke 12 

Analyses  and  physical  tests  of  samples 13 

Analysis  of  coal  and  coke 13 

Physical  tests  of  coke 13 

Softening  temperature  of  coke  ash 13 

Results  of  tests 14 

Discussion   of   tests 18 

Yield  of  coke  and  breeze '. 18 

Quality   of   coke 19 

Effect  of  size  of  coal  on  quality  of  coke 19 

Ash  content  of  coke 20 

Clinkering  tendency  of  ash 20 

Yield  of  gas  and  by-products 21 

Hydrogen  sulphide  in  the  gas 21 

Importance  of  gas  yield 22 

Advantage  of  mixing  the  coals 23 

Method  of  mixing  the  coals 23 


(5) 


ILLUSTRATIONS 


FIGURE  PAGE 

1.  Yield  of  entire  product  (coke  plus  breeze)  discharged  from  the 

retorts  14 

2.  Percentages  of  breeze  from  different  mixtures  of  coal 15 

3.  Effect  of  mixing  Illinois  and  Kentucky  coals  on  the  softening 

temperature  of  the  ash 20 


TABLES 


1.  Proximate  analyses  of  coals  used 10 

2.  Comparison  of  calculated  percentages  of  ash  in  mixtures  and 

percentages  obtained  from  analysis  of  laboratory  samples...  11 

3.  Data  from  the  tests 16, 17 


(6) 


CARBONIZATION  OF  ILLINOIS  GOALS 
IN  INCLINED  GAS  RETORTS 

By  F.  K.  Ovitz 


INTRODUCTION 

The  tests  described  in  this  paper  were  undertaken  by  the 
Bureau  of  Mines  as  part  of  cooperative  work  with  the  Illinois 
State  Geological  Survey  Division  and  the  Engineering  Experi- 
ment Station  of  the  University  of  Illinois  in  an  endeavor  to  obtain 
further  information  regarding  the  use  of  Illinois  coals  in  gas  re- 
torts. The  results  of  several  tests  with  Illinois  coals  by  gas  com- 
panies have  been  given  in  a  previous  report  of  the  Bureau.1 

Under  the  conditions  existing  in  the  winter  of  1917-18,  it  is 
desirable  to  use  as  much  as  possible  of  the  coal  that  is  mined 
locally  in  order  that  long  railroad  hauls  may  be  avoided  and  that 
the  burden  now  put  on  the  crowded  transportation  systems  of  the 
country  may  be  lightened.  Gas  manufacturers  of  the  middle  west 
during  the  past  year  have  seen  the  importance  of  a  local  supply 
of  coal  because  of  the  increasing  difficulty  of  obtaining  supplies 
of  eastern  gas  coal,  and  many  companies  have  considered  the  pos- 
sibility of  using  Illinois  coal  for  at  least  part  of  their  require- 
ments. 

A  high  yield  of  gas  of  good  quality  is  the  result  sought  in  the 
manufacture  of  illuminating  gas  in  retorts.  Coke,  tar,  and  am- 
monia are  by-products  that  are  recovered  in  order  to  increase  the 
economy  of  the  process.  Coke  is  the  chief  of  these  by-products, 
and  its  quality  should  be  given  consideration  in  selecting  and  car- 
bonizing the  coal. 

OBJECT  OF  TESTS 

The  immediate  object  of  the  tests  described  in  this  paper  was 
to  ascertain  how  the  quality  of  the  coke  obtained  was  affected  by 
mixing  Illinois  with  eastern  gas  coal.  Where  Illinois  coals  have 
been  used  for  gas  making,  the  usual  practice  has  been  to  charge 
a  part  of  the  retorts  with  Illinois  coal  alone  and  the  rest  with  an 
eastern  gas  coal.  The  coke  from  the  two  coals  was  kept  separate ; 
that  from  the  eastern  coals  was  sold  generally  for  domestic  pur- 


lOvitz,  F.  K.,  Coking  of  Illinois  coala:  Hull.  188,  Bureau  of  Mines,  pp.  54-64,    L91' 

(7) 


8  CARBONIZATION   OF  ILLINOIS   COAL 

poses,  while  that  from  the  Illinois  coal  alone  was  consumed  at  the 
plant,  usually  for  bench  fuel,  as  it  was  not  considered  as  good  as 
that  from  eastern  gas  coal. 

Another  object  of  the  tests  was  to  permit  the  use  of  better 
operating  conditions  than  are  possible  when  the  two  coals  are 
coked  separately.  Each  coal  requires  a  different  temperature  or 
different  length  of  time  in  the  retorts  to  carbonize  it  properly, 
and  in  practice  the  maintenance  of  conditions  adapted  to  give  the 
best  results  from  both  coals  is  difficult  if  not  impossible. 

SUMMARY  OF  RESULTS  AND  CONCLUSIONS 

Illinois  coal  mixed  with  Kentucky  coal  before  charging  yields 
better  coke  than  Illinois  coal  alone.  The  coke  has  a  more  uniform 
cell  structure,  is  denser,  more  homogeneous,  and  stronger. 

If  all  the  retorts  are  charged  with  the  same  mixture,  uniform 
operating  conditions  can  be  maintained  to  insure  proper  carboni- 
zation of  all  the  charges.  If,  however,  the  coals  are  used  unmixed, 
the  charges  of  Illinois  coal  require  either  a  higher  temperature  or 
a  longer  period  of  carbonization  than  the  charges  of  Kentucky 
coal. 

Coke  from  Illinois  coal  alone  contained  more  ash  and  had 
more  tendency  to  form  clinker  than  coke  from  a  mixture  of  Illi- 
nois coal  and  Kentucky  coal.  The  Kentucky  coal  had  a  low  ash 
content,  and  the  ash  had  a  high  softening  temperature;  conse- 
quently the  ash  content  of  the  coke  from  the  mixture  was  de- 
creased, and  the  softening  temperature  of  the  ash  was  raised. 

The  yield  of  coke  from  mixtures  was  larger  than  from  Illi- 
nois coal  alone,  and  increased  as  the  percentage  of  Kentucky  coal 
was  increased. 

The  amount  of  breeze  in  the  coke  made  from  unmixed  Illinois 
coal  was  greater  than  in  coke  from  mixtures.  The  amount  of 
breeze  from  mixtures  decreased  as  the  amount  of  Kentucky  coal 
in  the  mixture  was  increased. 

Mixtures  gave  higher  gas  yields  and  consequently  enabled 
greater  production  of  gas  with  a  given  equipment  than  could  be 
obtained  from  Illinois  coal  alone. 

There  is  a  considerable  supply  of  Illinois  coal  with  a  sulphur 
content  low  enough  to  permit  its  use  for  gas  making  without 
operating  trouble  from  sulphur. 

The  more  general  use  of  Illinois  coal  in  gas  plants  deserves 
careful  consideration  from  gas  manufacturers.  At  many  plants 
in  the  central  west  the  cost  of  producing  the  gas  can  be  consider- 


DESCRIPTION   OF  TESTS  9 

ably  reduced  by  using  either  Illinois  coal  alone  or  by  mixing  with 
it  another  coal. 

ACKNOWLEDGMENTS 

Thanks  are  due  M.  L.  Harry,  manager  of  the  Decatur  Rail- 
way and  Light  Company  for  extending  the  use  of  the  gas  plant 
facilities  for  the  tests  and  for  many  privileges  and  courtesies. 
The  author  is  indebted  to  John  Sieberz,  works  superintendent  of 
the  gas  plant,  for  assistance  in  the  preparations  for  the  test,  in- 
terest in  the  work,  and  help  in  overcoming  difficulties. 

Acknowledgments  are  due  F.  W.  Bedard,  gas  engineer,  and 
R.  B.  Richardson,  assistant  gas  engineer,  of  the  Illinois  Traction 
System,  and  Edward  H.  Taylor  of  Chicago  for  cooperation  and 
advice. 

0.  P.  Hood,  chief  mechanical  engineer  of  the  Bureau  of 
Mines,  took  an  active  interest  in  the  work.  The  chemical  analyses 
and  physical  tests  were  made  under  the  direction  of  A.  C.  Field- 
ner,  chemist,  of  the  Bureau  of  Mines. 

Credit  is  due  to  F.  P.  Strauch,  holder  in  1916-1917  of  the 
Illinois  Gas  Association  fellowship  at  the  University  of  Illinois, 
who  assisted  in  most  of  the  tests  and  in  compiling  the  resulting 
data.  The  Chicago,  Wilmington  and  Franklin  Coal  Company 
donated  the  car  of  Franklin  County  coal  that  was  used  in  the 
tests. 

DESCRIPTION  OF  TESTS 

Tests  of  Illinois  coal  unmixed  and  of  mixtures  of  Illinois  coal 
with  20  to  80  per  cent  of  Harlan  County,  Kentucky,  coal  were 
made  in  order  to  study  the  effect  of  mixing  on  the  quality  of  the 
coke.  The  coals  used  were  a  part  of  the  regular  output  of  the 
mines.  No  attempt  was  made  to  maintain  any  special  operating 
conditions  that  might  suit  the  Illinois  coal,  the  mixtures  being 
carbonized  under  the  regular  plant  conditions  used  with  Ken- 
tucky coal.  Temperatures  were  measured  in  the  retorts.  Samples 
of  the  coal  and  coke  were  collected  and  subjected  to  chemical  and 
physical  tests,  including  the  softening  temperature  of  the  ash. 
With  the  equipment  at  hand  the  yield  and  quality  of  the  gas  from 
the  coal  mixtures  could  not  be  obtained,  as  the  gas  from  the 
charges  in  the  test  retorts  became  mixed  with  gas  from  the  other 
retorts  before  purification  and  metering. 


1(1 


CARBONIZATION   OF  ILLINOIS   COAL 


Coal  Used 

The  Illinois  coal  used  in  the  tests  came  from  three  districts 
as  follows:  (1)  Perry  County,  bed  No.  6,  2-inch  lump;  (2) 
Franklin  County,  bed  No.  6,  run-of-mine;  (3)  White  County,  bed 
No.  6,  run-of-mine.  With  these  a  gas  coal  from  Harlan  County, 
Ky.,  was  mixed. 

For  most  of  the  charges  the  coals  were  crushed  in  a  roll 
crusher  set  to  produce  1%-inch  pieces  as  maximum  size.  Thirty 
per  cent  of  the  product  was  smaller  than  i/2-mcn  size.  A  few 
charges  were  made  with  smaller  sizes  in  an  endeavor  to  deter- 
mine the  effect  of  size  of  coal  on  the  strength  of  the  coke  pro- 
duced; the  results  were  not  conclusive  because  of  difficulties  in 
charging  these  small  sizes. 

The  proximate  analyses  of  the  coals  used  are  given  in  Table 
1  following: 

Table  1. — Proximate  analyses  of  coals  used 
(As  received  basis) 


Constituent 

Perry 
County, 
Illinois 

Franklin 
County, 
Illinois 

White 
County, 
Illinois 

Harlan 

County, 

Kentucky 

Moisture 

Volatile  matter 

Per  cent 

10.80 

32.81 

47.22 

9.17 

M 

Per  cent 

11.74 

29.93 

48.52 

9.81 

1.39 

Per  cent 

7.20 

35.70 

47.51 

9.59 

3.49 

Per  cent 

4.68 

37.06 

Fixed  carbon 

53.72 

Ash 

Sulphur 

4.54 
.93 

Retort 

S 

The  tests  were  made  in  the  spring  of  1917  at  the  plant  of  the 
Decatur  Railway  and  Light  Company,  Decatur,  Illinois,  where 
the  carbonizing  equipment  consists  of  six  full-depth  benches  of 
sixes,  with  inclined  sectional  silica  retorts  15  feet  long,  25  inches 
wide,  and  16  inches  high,  set  at  an  angle  of  40°  with  the  floor. 
Each  retort  holds  a  charge  of  approximately  one  thousand  pounds 
of  coal.  The  inside  top  retort  in  an  end  bench  was  selected  for  the 
test  charges  because  its  use  did  not  interfere  with  the  operation 
of  other  retorts.  A  complete  description  of  the  plant  is  given  in 
the  proceedings  of  the  Illinois  Gas  Association  for  1915. x 


1Richardson,  R.  B.,  Inclined  retorts:   Proc.  Illinois  Gas  Assoc,  p.  24,  1915. 


DESCRIPTION   OF   TESTS 


11 


Measurement  of  Temperatures 
The  temperatures  inside  the  retort  were  measured  with  a 
Lunette  optical  pyrometer,  which  was  compared  with  a  Wanner 
optical  pyrometer.  Two  observations  were  made  immediately  be- 
fore charging  the  coal  and  two  immediately  after  discharging  the 
coke.  The  temperature  was  not  uniform  throughout  the  retort; 
usually  the  hottest  part  was  about  one-third  of  the  distance  from 
the  bottom  end  and  the  coolest  part  was  near  the  top.  The  read- 
ings were  made  by  sighting  the  pyrometer  alternately  on  opposite 
walls  near  the  middle  of  the  retort.  The  average  of  all  the  read- 
ings was  considered  as  approximately  representing  the  tempera- 
ture of  the  middle  part  of  the  retort.  During  temperature  obser- 
vations the  bottom  end  of  the  retort  was  closed  to  prevent  an 
inrush  of  cold  air  lowering  the  temperature.  The  top  of  some 
charges  was  not  completely  carbonized  and  then  smoke  and  flame 
from  pieces  of  partly  carbonized  coal  remaining  in  the  retort 
made  satisfactory  observations  difficult. 

Mixing  and  Sampling  Coal 
The  charges  were  prepared  by  making  a  pile  of  the  number 
of  shovelfuls  of  Illinois  and  Kentucky  coal  required  to  fill  the  test 
retort,  and  were  further  mixed  by  rehandling.  For  example,  if 
60  per  cent  of  Illinois  coal  was  required  in  the  mixture,  three 
shovelfuls  of  Illinois  and  two  of  Kentucky  coal  were  alternately 
thrown  on  the  pile  until  a  charge  was  obtained.  The  coal  was 
then  shoveled  into  an  elevator  that  delivered  it  to  one  of  a  num- 
ber of  over-head  bins  whence  it  was  loaded  into  the  charging 
buggy  and  taken  to  the  retorts.  That  the  coals  were  thoroughly 
mixed  is  shown  by  comparing  the  calculated  percentages  of  ash 
with  the  percentages  obtained  from  analysis  of  the  laboratory 
samples,  as  given  in  Table  2. 

Table  2. — Comparison  of  calculated  percentages  of  ash  in  mixtures  and 
percentages  obtained  from  analysis  of  laboratory  samples 


Mixture" 


Ash  from 
analysis 


Calculated 
ash 


80  per  cent  Perry  County 

60  per  cent  Perry  County 

50  per  cent  Perry  County 

40  per  cent  Perry  County 

20  per  cent  Perry  County 
80  per  cent  Franklin  County 
60  per  cent  Franklin  County 
40  per  cent  Franklin  County 
20  per  cent  Franklin  County 


Per  cent 
8.59 

7.71 
6.74 
5.88 
4.83 
9.08 
7.80 
6.77 
5.54 


Per  cent 
8.24 
7.32 
6.85 
6.39 
5.47 
8.76 
7.70 
6.65 
5.59 


"Percentages  of  Kentucky 
coal  given. 


'I   u  ed   equal   LOO   per  cenl    minus   percentages  of  Illinois 


12  CARBONIZATION   OF  ILLINOIS   COAL 

Samples  for  analysis  were  taken  by  setting  aside  every  tenth 
shovelful  while  the  coal  was  being  transferred  to  the  elevator,  a 
sample  of  about  100  pounds  representing  each  charge  of  approxi- 
mately 1,000  pounds.  Each  sample  was  alternately  crushed  and 
reduced  by  quartering  to  a  sample  weighing  about  three  pounds, 
which  was  shipped  to  the  laboratory. 

Weighing  the  Coal 

The  charging  buggy  was  so  equipped  with  hooks  that  it  could 
be  raised  by  aid  of  pulley  blocks  and  attached  to  a  steelyard.  The 
weight  of  the  loaded  buggy  minus  the  weight  of  the  empty  buggy 
gave  the  weight  of  the  coal  charged. 

Handling  and  Sampling  Coke 

The  coke  was  drawn  from  the  retort  directly  into  a  hopper, 
where  it  was  quenched  with  water;  then  it  was  dumped  into  a 
coke  car,  in  which  it  remained  for  12  hours  before  weighing,  in 
order  to  allow  the  water  to  drain  off.  It  was  weighed  on  the  plat- 
form scale  in  daily  use  at  the  plant,  and  immediately  afterward 
was  placed  on  a  wooden  platform,  where  it  was  sampled  and  the 
amount  of  breeze  determined  as  quickly  as  possible. 

The  coke  was  handled  with  a  fork  having  tines  IV2  inches 
apart.  A  sample  for  analysis  and  physical  tests  was  obtained  by 
throwing  every  fourth  or  fifth  forkful  into  a  barrel.  This  barrel 
when  filled  was  covered  and  shipped  to  the  Bureau's  laboratory 
at  Pittsburgh.  A  sample,  weighing  approximately  50  pounds,  for 
moisture  determination,  was  obtained  in  the  same  way.  The 
moisture  sample  was  placed  in  an  oven  heated  to  about  38°  C. 
and  dried  to  constant  weight.  A  portion  of  this  partly  dried 
sample  was  ground  to  pass  a  60-mesh  sieve  and  taken  to  the  labo- 
ratory, where  the  moisture  still  remaining  was  determined  in  an 
oven  heated  to  110°  C.  The  sum  of  these  two  moisture  determina- 
tions calculated  to  the  same  weight  basis  gave  the  total  moisture 
in  the  coke  at  the  time  of  weighing,  from  which  the  yield  of  dry 
coke  could  be  calculated. 

The  coke  remaining  on  the  platform  after  forking  was 
passed  over  a  one-half  inch  square-hole  screen  and  the  undersize 
was  taken  as  breeze. 


DESCRIPTION   OF   TESTS  13 

ANALYSES  AND  PHYSICAL  TESTS  OF  SAMPLES 

Analysis  of  Coal  and  Coke 

The  samples  of  coal  and  coke  were  analyzed  at  Pittsburgh  by 
the  methods  described  in  Technical  Papers  8  and  76.1 

Physical  Tests  of  Coke 

The  true  and  apparent  specific  gravity  of  the  coke  were  ob- 
tained by  the  methods  described  in  Technical  Paper  8.1  The  re- 
lative breakage  was  determined  by  the  shatter  test,  as  described 
in  Tech.  Paper  50. 2  In  separating  the  sizes,  the  2-inch  screen  was 
shaken  until  all  undersize  had  passed  through. 

Softening  Temperature  of  Coke  Ash 

The  softening  temperature  of  the  ash  gives  an  idea  of  the 
liability  to  form  clinkers  when  the  coke  is  burned.  It  was  deter- 
mined in  a  gas-fired  furnace,  according  to  the  method  described 
in  Bulletin  129. 3  A  reducing  atmosphere  maintained  in  the  fur- 
nace by  adjustment  of  the  gas  and  air  supply  kept  the  iron  in  the 
ferrous  state  so  that  the  melting  points  of  the  ash  were  the  low- 
est. 

A  portion  of  the  completely  oxidized  ash,  ground  to  pass  a 
200-mesh  sieve,  was  moistened  with  a  10  per  cent  dextrine  solu- 
tion, worked  into  a  plastic  mass,  and  moulded  into  triangular 
pyramids  each  %  inch  high  and  having  a  base  that  measured  1/i 
inch  on  each  side.  The  pyramids  were  mounted  in  a  refractory 
base  and  after  all  the  moisture  was  driven  off  they  were  ignited 
in  a  muffle  furnace  at  a  dull  red  heat  to  burn  the  dextrine. 

The  ignited  pyramids  were  placed  in  a  fire-clay  crucible  and 
put  in  the  furnace.  Holes  in  the  furnace  jacket  and  the  crucible 
permitted  observation,  and  temperature  measurements.  The  tem- 
perature of  the  furnace  was  raised  gradually  to  800°  C. ;  then  a 
rate  of  increase  of  not  less  than  5°  nor  more  than  10°  C.  a  minute 
was  maintained  until  the  cone  flattened.  Temperature  measure- 
ments were  made  (1)  at  the  initial  deformation  of  the  pyramid, 
(2)  when  the  pyramid  had  fused  to  a  spherical  lump,  and  (3) 
when  the  pyramid  had  melted  to  a  flat  layer. 


1Stanton,  F.  M.,  and  Ficldncr,  A.  C,  Methods  of  analyzing  coal  and  coke:  Tech. 
Paper  8,  Bureau  of  Mines,  42  pages,  1913.  Fieldner,  A.  C,  Notes  on  sampling  and  analysis 
of  coal,  Paper  76,  Bureau  of  Mines,  61  pages,  1914. 

2Belden,  A.  W.,  Metallurgical  coke:  Tech.  Paper  50.  Bureau  of  Mines,    is  pages,   1913. 

3Fieldner,  A.  C,  Hall,  A.  H.,  and  Field,  A.  L„  The  fusibility  of  coal  ash  and  the  de- 
termination of  the  softening  temperature,  1917. 


14  CARBONIZATION  OF  ILLINOIS   COAL 

RESULTS  OF  TESTS 

The  results  of  tests  made  with  mixtures  of  Illinois  coals, 
which  are  the  averages  of  two  individual  charges,  unless  other- 
wise stated,  are  given  in  Table  3.  In  each  group  the  tests  are 
arranged  according  to  the  percentage  of  Illinois  coal. 

An  explanation  of  the  table  is  given  in  the  following  items : 

Column  1  shows  only  the  percentage  of  Illinois  coal,  the  remainder  of 
the  mixture  being  coal  from  Harlan  County,  Kentucky.  t 

Column  2  gives  the  average  weight  of  the  coal  charged,  including 
moisture. 

Column  3,  period  of  carbonization,  represents  the  average  time  of  two 
test  charges. 

Column  4,  temperature  inside  of  the  retorts,  represents  the  average  of 
four  readings,  taken  with  the  pyrometer  sighted  on  the  sides  of  the  retort 
near  the  middle. 

Column  5  gives  the  yield  of  coke  as  expressed  on  a  basis  of  dry  coke 
obtained  from  dry  coal.  The  term  "coke"  designates  the  portion  of  the  pro- 
duct from  the  retorts  which  was  the  oversize  of  a  one-half  inch  square-hole 
screen. 

Column  6  shows  the  yield  of  breeze  as  expressed  in  percentage  of  dry 
breeze  obtained  from  dry  coal.  The  breeze  is  the  undersize  of  the  one-half 
inch  square-hole  screen. 

In  column  19  the  percentage  of  coke  substance  by  volume  is  computed 
from  the  apparent  and  true  specific  gravities  as  follows: 

Apparent  specific  gravity 

— ; X  100  =  percentage  of  coke  substance.   The 

True  specific  gravity 

percentage  of  coke  substance  subtracted  from  100  gives  the  per  cent  of  cell 
space. 

Columns  20  and  21  give  the  results  of  the  shatter  test.  In  the  tests  the 
screen  was  shaken  until  all  undersize  passed  through. 

In  column  22  the  softening  temperature  of  the  ash  from  the  coke  rep- 
resents the  temperature  at  which  the  ash  collapsed  to  a  spherical  lump  after 
being  heated  at  a  definite  rate. 

In  column  23  the  softening  interval  of  the  ash  represents  the  differ- 
ence between  the  temperature  at  which  deformation  was  first  obsrved  and 
the  softening  temperature. 

In  column  24  the  flowing  interval  represents  the  difference  between 
the  softening  temperature  and  the  temperature  at  which  the  cone  dis- 
appeared, the  fused  ash  forming  a  flat  surface. 

DISCUSSION  OF  TESTS 

The  coals  used  in  these  tests  were  carbonized  under  condi- 
tions that  suited  coal  from  Harlan  County,  Kentucky.  Similar 
tests  with  Illinois  coal  or  mixtures  of  Illinois  coal  in  another  type 
of  retort  or  under  conditions  more  adapted  to  suit  it  would  lead 


DISCUSSION  OF  TESTS 


15 


to  different  results.  The  quality  of  retort  coke  depends  to  a  con- 
siderable degree  upon  the  temperature  of  the  retorts  and  time  of 
carbonization,  and  if  these  factors  were  adjusted  to  better  suit 
Illinois  coal,  stronger  and  harder  coke  could  undoubtedly  be  ob- 
tained. 


70  - 

/ 

1 

* 

70 

i 

J 

65  - 

Illinois      100 
Kentucky    0 


20 


60  40 

40  60 

COAL  IN  MIXTURE.PEK  CENT 


20 


0 

100 


Fig.  1. — Yield  of  entire  product  (coke  plus  breeze)  discharged  from 
the  retorts:  A,  Illinois  coal  from  Franklin  County;  B,  Illinois  coal  from 
Perry  County. 


Yield  of  Coke  and  Breeze 


The  term  "coke"  is  frequently  used  in  a  general  sense  with- 
out a  definite  meaning.  In  this  paper,  coke  is  used  to  designate 
that  part  of  the  entire  product  discharged  from  the  retorts  that 
was  the  oversize  of  a  one-half  inch  square-hole  screen,  and  breeze 
is  the  undersize  of  a  one-half  inch  square-hole  screen.  The  entire 
product  from  the  retort  is  coke  plus  breeze.  This  usage  is  some- 
what arbitrary,  but  is  rather  widely  accepted. 


16 


CARBONIZATION   OF   ILLINOIS   COAL 


Table 


-Data  from 


Analyses   of  coal 

as  charged 

be 

u 

o 

a; 
& 

a 
o 

o 
c 
.2 

Q 

CD     ' 

IE 
g 

i| 

ft  o 

£ 

H 

si 

o  w 

^  u 

O  rg 

a>  rt 
CD  o 

.2  § 

03 
O 
U 

O 

C 

0) 

'o 

3 

2 

'-P    HI 

73    O 

M 

< 

u 

a 

l 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

ILLINOIS  COAL 

Pounds 

Hours 

Deg.F 

Pet. 

Pet. 

Pet. 

Pet. 

Pet. 

Pet. 

Pet. 

Perry    County 

"959 

7.5 

1874 

60.8 

5.7 

9.18 

34.35 

49.12 

7.35 

.81 

Perry    County 

876 

7.5 

1927 

58.2 

6.5 

10.80 

32.81 

47.22 

9.17 

.66 

80   per  cent  Perry   Co 

"951 

7.5  ■ 

1853 

60.0 

5.6 

9.22 

33.75 

48.44 

8.59 

.68 

60  per  cent  Perry   Co 

919 

7.5 

1902 

61.2 

5.7 

7.48 

34.63 

50.18 

7.71 

.70 

50   per  cent  Perry   Co 

902 

7.75 

1687 

62.3 

5.2 

6.96 

35.23 

51.07 

6.74 

.80 

40  per  cent  Perry  Co 

823 

7.75 

1811 

64.6 

3.6 

5.06 

36.64 

52.42 

5.88 

.85 

20  per  cent  Perry  Co 

967 

8.75 

1806 

66.2 

3.3 

4.50 

36.67 

54.00 

4.83 

.76 

Franklin  County 

964 

7.00 

1772 

58.8 

7.2 

11.74 

29.93 

48.52 

9.81 

1.39 

80  per  cent  Franklin  Co. 

6c1048 

7.5 

1597 

57.5 

9.5 

7.20 

33.70 

50.02 

9.08 

.91 

60  per  cent  Franklin  Co. 

1021 

7.5 

1717 

61.9 

5.6 

6.72 

34.62 

50.86 

7.80  ■ 

.95 

40  per  cent  Franklin  Co. 

d890 

7.5 

1747 

62.5 

5.8 

4.50 

36.23 

52.50 

6.77 

1.03 

20  per  cent  Franklin  Co. 

d970 

7.5 

1780 

65.6 

4.1 

4.87 

35.88 

53.71 

5.54 

.94 

White    County 

6942 

7.0 

1852 

61.0 

4.4 

7.20 

35.70 

47.51 

9.59 

3.49 

KENTUCKY  COAL 

Harlan    County 

898 

7.5 

1775 

66.6 

4.8 

4.68 

37.06 

53.72 

4.54 

.93 

"Size  of  coal  charged,  2-inch. 
6Single  test. 

'Temperature  low   from  charge  of  fuel  in  the  generators  ;  charge  not  completely   car- 
bonized. 

''Top  of  charge  not  completely  carbonized. 


DISCUSSION  OF  TESTS 


17 


the  tests 


Analyses  of  coke 

Physical  properties  of  coke 

QJ 

09 

< 

3 

"5 

C/2 

cy 

0? 

>> 

'3.5 

ft  > 
fl  * 

V 

w 

C 

w  to 

o| 

Shatter 
test 

CU 

W*5 

Softening- 
interval 
of  ash 

3 

CO 

'5 

u  w  o 

MJ5  c 

CU    y   a 

T3  c  a, 

<5."T  v 
3n  oi 

111 

7*  c  '-' 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

Pet. 

Pet. 

Pet. 

Pet. 

Pet. 

Pet. 

Pet. 

Pet. 

Deg.  F 

Deg.  F 

Deg.  F 

1.46 

2.69 

83.26 

12.59 

.72 

.88 

1.88 

47. 

24.2 

75.8 

2278 

137 

198 

2.40 

3.06 

81.0 

13.54 

.65 

.88 

1.85 

48. 

21.1 

78.9 

2364 

80 

122 

2.45 

3.69 

81.42 

12.44 

.62 

.88 

1.85 

48. 

21.1 

78.9 

2351 

131 

151 

2.14 

2.84 

83.16 

11.86 

.66 

.89 

1.82 

49. 

27.:; 

72.7 

2356 

265 

127 

2.04 

3.75 

83.79 

10.42 

.67 

.87 

1.79 

49. 

30.8 

69.2 

2326 

150 

94 

.85 

2.39 

87.19 

9.57 

.66 

.90 

1.83 

49. 

24.4 

75.6 

2414 

134 

89 

1.49 

2.70 

88.10 

7.71 

.60 

.95 

1.82 

52. 

22.3 

77.7 

2525 

96 

125 

.    2.05 

4.65 

77.99 

15.31 

1.07 

.89 

1.85 

48. 

30.0 

70.0 

2185 

139 

218 

.82 

4.71 

81.72 

12.75 

.92 

.90 

1.80 

50. 

26.0 

74.0 

2201 

106 

216 

.82 

4.20 

83.77 

11.21 

.86 

.89 

1.85 

48. 

26.7 

78.8 

2292 

108 

174 

.54 

4.89 

83.85 

10.72 

.88 

.95 

1.81 

52. 

27.0 

7:;.o 

2285 

70 

130 

1.98 

3.49 

86.19 

8.34 

.84 

.91 

1.80 

51. 

31.0 

69.0 

2875 

135 

140 

2.16 

3.59 

80.23 

14.02 

2.56 

.84 

1.85 

45. 

24.5 

75.5 

1 988 

36 

362 

1.86 

2.97 

88.20 

6.97 

.67 

.91 

1.82 

50. 

30.4 

69.6 

2456 

74 

103 

18 


CARBONIZATION   OF  ILLINOIS   COAL 


Figures  1  and  2  show  the  yield  of  entire  product  from  the 
retorts  and  the  percentage  of  breeze  from  different  mixtures  of 
coal.  The  charges  ranged  from  Illinois  coal  unmixed  through  dif- 
ferent mixtures  of  Illinois  and  Kentucky  coal  to  Kentucky  coal 
unmixed.  With  Illinois  coal  alone,  the  entire  product  from  the 
retorts  averaged  65.5  per  cent  of  the  coal  used,  calculated  on  a 
basis  of  dry  coke  and  breeze  from  dry  coal ;  with  Kentucky  coal 


A 

/\ 

^-          X                                            A^ 

/               \ 

Ztlt      £               \L 

-           /                  \ 

y                         A 

■/                         \t- 

-/                               X 

-7                         v 

-Z                          X 

7                                                              \ 

7                                        5 

\ 

3 

£                                                            it 

3 

it l -====—< 

V--—  -    -*     --         ==  :    : 

\ 

%  -&•        =.-=">h" 

^.    ^^-^ 

^r* 

'K, 

H~-- 

^ 

^ 

NNl ""^ 

S*H 

5                                                                                              \ 

s                                  y 

x                              S 

V                            * 

X                            J3           ' 

v                      S 

X^                 y 

%                        1 — i— u 

Illinois    100 

80 

60 

40 

Kentucky  0 

20 

40 

60 

COAL  IN  MIXTURE, 

PER  CENT 

20 


0 
100 


Fig.  2. — Percentages  of  breeze  from  different  mixtures  of  coal:    A,  Illi- 
nois coal  from  Franklin  County;  B,  Illinois  coal  from  Perry  County. 


alone,  the  average  yield  on  the  same  basis  was  71.4  per  cent.  The 
yield  of  the  entire  product  increased  with  decreasing  percentages 
of  Illinois  coal ;  the  lowest  yield  was  from  Illinois  coal  unmixed. 

The  amount  of  breeze  was  roughly  proportional  to  the  per- 
centage of  Illinois  coal  in  the  mixture;  and  increased  with  in- 
creasing percentages  of  Illinois  coal.  An  exception  to  this  rule 
was  the  amount  of  breeze  from  a  mixture  of  20  per  cent  Illinois 


DISCUSSION   OF  TESTS  19 

and  80  per  cent  Kentucky  coal  which  was  uniformly  less  than 
from  Kentucky  coal  alone.  Some  of  the  duplicate  tests  showed 
considerable  variation  in  the  proportion  of  breeze,  probably  be- 
cause the  conditions  of  carbonization  differed.  High  tempera- 
tures and  long  carbonization  tend  to  produce  strong  hard  coke. 
The  same  temperature  and  same  period  of  carbonization  will  pro- 
duce harder  coke  from  a  small  charge  than  from  a  large  charge. 
Inability  to  control  these  factors  continually  caused  differences 
in  the  strength  of  the  coke. 

The  Illinois  coals  tested  showed  little  difference  in  the  yield 
of  entire  retort  product ;  Perry  County  coal  gave  a  little  less  than 
Franklin  County  coal,  but  the  latter  produced  slightly  more 
breeze,  so  that  the  yield  of  merchantable  coke  was  about  the  same 
from  each  coal.  In  the  one  test  made,  coal  from  White  County 
gave  about  the  same  results  as  Perry  County  coal. 

Quality  of  Coke 

The  coke  from  mixtures  was  denser  and  harder,  had  a  more 
uniform  cell  structure,  and  did  not  contain  as  much  unfused  ma- 
terial as  coke  from  Illinois  coal  alone.  A  gradual  improvement 
in  the  appearance  of  the  coke  was  noticeable  until  the  proportion 
of  Illinois  coal  reached  60  per  cent ;  above  this  point  no  improve- 
ment of  appearance  was  evident.  The  percentages  of  coke  sub- 
stance as  given  in  Table  3,  indicate  that  coke  from  the  mixtures 
was  somewhat  denser  than  coke  from  Illinois  coal  alone.  It  was 
also  heavier  and  came  from  the  retort  in  larger  pieces.  Mixing 
the  coal  lowered  the  ash  content  and  raised  its  softening  tempera- 
ture, thus  improving  the  coke  as  fuel. 

The  shatter  test  gave  such  variable  results  with  coke  from 
duplicate  tests  that  the  strength  of  the  coke  could  not  be  judged 
from  them.  Temperature,  time  of  carbonization,  weight  of 
charge,  and  like  factors  apparently  affected  the  strength  more 
than  did  mixing. 

Effect  of  Size  of  Coal  on  Quality  of  Coke 

To  determine  the  effect  of  size  of  the  coal  on  quality  of  the 
coke,  tests  were  made  with  coal  smaller  than  ty>  inch,  but  difficul- 
ties in  handling  and  charging  small  sizes  prevented  definite  re- 
sults from  being  obtained.  The  writer  believes  that  fine  crushing 
will  improve  the  strength  and  appearance  of  coke  from  Illinois 
coals.  Examination  of  coke  made  from  Illinois  coal  above  3-inch 
size  shows  that  certain  easily  recognized  layers  apparently  do  not 


20 


CARBONIZATION   OF  ILLINOIS   COAL 


coke  but  remain  as  unfused  layers,  along  which  the  coke  has  a 
tendency  to  break.  They  are  the  dull  black  layers  of  the  coal 
which  do  not  possess  the  coking  property.  A  stronger  and  more 
uniform  coke  probably  would  be  obtained  by  crushing  the  coal 
and  mixing  the  coking  and  non-coking  layers. 


O      _j 

r- 

2 

/ 

j 

/                                    ^ 

/                               -7 

r                                             7 

_/                                           /* 

t                                    S     - 

j-                  y 

-,    t                J 

-i>        —                  '»S                   /        /                                                         / 

> s-,     -f                    /~ 

«*-'                                   ^Jl                     -7 

**"                                          ^~                     Z 

-*-                                                                      / 

2300                                                                                                                                                    -y 

it          -/  ^  -t              / 

y       ^                V 

S                   vv          E    ./ 

S                ^      z 

/                      ^  2 

*                         ^ 

/_ 

*_ 

2200                                -<2 

c> — "" 

Illinois     100 

80 

60                             40 

Kentucky   0 

20 

40                             60 

COAL  IN  MIXTURE,  PER  CENT 

20 


0 

100 


Fig.  3. — Effect  of  mixing  Illinois  and  Kentucky  coals  on  the  softening 
temperature  of  the  ash:  A,  Illinois  coal  from  Perry  County;  B,  Illinois  coal 
from  Franklin  County. 

Ash  Content  of  Coke 

The  ash  content  of  coke  from  Illinois  coals  tested  was  12.5 
to  15.3  per  cent;  whereas  the  ash  content  of  the  coke  from  Ken- 
tucky coal  was  about  7.0  per  cent  only.  This  suggests  one  advan- 
tage in  mixing  the  coals.  When  equal  parts  of  Perry  County  and 
Kentucky  coal  were  mixed,  the  ash  content  of  the  coke  was  10.4 
per  cent,  a  reduction  of  about  one-quarter  as  compared  with  coke 
from  Perry  County  coal  unmixed.  A  high  ash  content  not  only 
reduces  the  heating  value  of  coke  but  increases  clinkering  trouble. 

Clinkering  Tendency  of  Ash 

The  softening  temperature,  softening  interval;  and  flowing 
interval  of  the  ash  (Table  3)  give  an  idea  of  the  tendency  of  the 


DISCUSSION  OF  TESTS  21 

coke  to  clinker  when  burned.  Coke  ash  from  the  Illinois  coals 
tested  had  softening  temperatures  of  1983°  to  2364°  F.  Coke  ash 
from  the  Kentucky  coal  had  a  softening  temperature  of  2456°  F. 
For  this  reason  coke  from  Illinois  coal  can  be  expected  to  show  a 
greater  tendency  to  form  clinkers. 

Figure  3  shows  how  the  softening  temperature  of  the  ash 
is  affected  by  mixing  the  coal.  In  all  the  tests  the  raising  of  the 
softening  temperature  of  the  ash  was  roughly  proportional  to  the 
percentage  of  Kentucky  coal  added.  Hence  mixing  the  coals  re- 
duces the  tendency  of  the  coke  to  clinker,  thus  decreasing  one  of 
the  disadvantages  of  using  coke  from  Illinois  coal. 

Yield  of  Gas  and  By-Products 

With  the  equipment  available  for  these  tests  the  yield  of  gas 
and  by-products  could  not  be  determined.  However,  results  ob- 
tained by  several  gas  companies  that  have  experimented  with  Illi- 
nois coals,  show  that  4  to  4.5  cubic  feet  of  gas,  having  a  heating 
value  of  585  to  600  B.t.u.  can  be  obtained  from  each  pound  of  coal. 
The  yield  of  ammonia  was  5  to  6  pounds  and  that  of  tar  10  to  12 
gallons  a  ton  of  coal.  The  details  of  some  of  these  tests  are  given 
in  Bulletin  138  of  the  Bureau  of  Mines.1 

A  larger  yield  of  gas  might  be  obtained,  but  the  excess  would 
be  mostly  hydrogen,  which  has  a  low  heating  value  per  cubic  foot 
and  would  lower  the  quality  of  the  gas  below  the  standard  fixed 
by  law.  It  is,  therefore,  advisable  to  stop  carbonization  before  all 
of  the  hydrogen  has  been  driven  off. 

Illinois  coals,  probably  because  of  a  higher  combined  mois- 
ture content,  yield  more  ammonia  than  most  eastern  coals.  With 
good  operating  conditions  a  yield  of  6  pounds  of  ammonia  can  be 
obtained  per  ton  of  Illinois  coal  coked. 

The  quality  of  the  tar  depends  upon  the  amount  of  cracking 
in  the  volatile  products,  and  this  is  controlled  by  the  conditions 
of  carbonization  and  the  kind  of  retort.  In  general,  tar  from 
Illinois  coal  compares  well  with  other  tars  produced  by  the  same 
process. 

Hydrogen  Sulphide  in  the  Gas 

The  sulphur  content  of  the  Perry  County  coal  was  0.66  per 
cent  and  of  the  Franklin  County  coal  was  1.39  per  cent.  Assum- 
ing that  one-half  of  the  sulphur  goes  into  the  gas  during  the  pro- 
cess of  carbonization,  the  Perry  County  coal  should  yield  gas  hav- 


^vitz,  F.  K.,  Coking  of  Illinois  coals:  Bull.  138,  Bureau  of  Mines,  pp.  54-64,  1917. 


22  CARBONIZATION   OF  ILLINOIS   COAL 

ing  about  600  grains  of  hydrogen  sulphide  per  100  cubic  feet  of 
unpurified  gas,  and  the  Franklin  County  coal  should  yield  gas 
having  a  little  more  than  twice  that  amount.  Such  quantities  of 
hydrogen  sulphide  are  not  excessive.  The  coal  from  White 
County  contained  3.49  per  cent  of  sulphur  and  yielded  gas  that 
contained  too  much  hydrogen  sulphide  to  be  handled  efficiently 
by  the  ordinary  purifying  system. 

An  area  of  at  least  75  square  miles  in  Franklin  and  William- 
son counties  and  a  small  area  in  Jackson  County  contain  coal  of 
a  low  enough  sulphur  content  to  permit  its  use  for  gas  making 
without  excessive  trouble  from  hydrogen  sulphide.  There  are 
probably  other  areas  in  Illinois  that  can  produce  coal  with  less 
than  1.5  per  cent  sulphur  if  special  care  is  taken  in  mining  and 
preparation. 

Importance  of  Gas  Yield 

The  gas  yield  from  Illinois  coal  is  about  20  to  25  per  cent  less 
than  that  obtained  from  eastern  gas  coals.  This  means  that  about 
20  per  cent  more  coal  needs  to  be  carbonized,  the  labor  cost  will 
be  larger,  and  the  retort  capacity  will  have  to  be  greater  for  the 
same  amount  of  gas.  Coal-gas  benches  are  usually  worked  to 
capacity  at  all  times,  and  it  does  not  seem  possible  to  increase  the 
charge  or  decrease  the  period  of  carbonization  enough  to  make 
up  for  the  difference  in  capacity  occasioned  by  the  use  of  Illinois 
coal.  For  example,  if  a  retort  carbonizes  400  pounds  of  coal 
yielding  5  cubic  feet  per  pound  in  4  hours,  it  would  not  be  pos- 
sible to  increase  the  charge  or  decrease  the  coking  period  enough 
to  make  the  same  amount  of  gas  from  a  coal  yielding  4  cubic  feet. 
Additional  retorts  would  be  required,  and  the  consumption  of 
bench  fuel  would  be  larger 

The  bench  fuel  is  reported  customarily  as  the  number  of 
pounds  of  fuel  used  for  heating  the  retorts  per  unit  of  coal  car- 
bonized. This  method  fails  to  take  into  account  the  gas  yield 
from  the  coal.  As  the  superintendent  is  concerned  with  the  cost 
of  gas  in  the  holder,  the  bench  fuel  used  per  unit  of  gas  would 
seem  to  be  a  better  standard,  as  it  allows  the  proportionate  cost 
of  fuel  for  carbonizing  coals  with  different  gas  yields  to  be  ob- 
tained at  a  glance. 

There  may  be  gas  plants  in  which  the  capacity  of  the  retorts 
could  be  increased  enough  to  supply  the  required  gas  by  using 
coal  yielding  4  cubic  feet  of  gas  a  pound.  Where  such  conditions 
exist  it  is  advisable  to  inquire  into  the  relative  prices  of  Illinois 
and  other  gas  coals,  as  the  difference  in  price  may  more  than  off- 


DISCUSSION  OF  TESTS  2?, 

set  the  lower  gas  yield  from  Illinois  coal.  Even  when  the  retort 
capacity  is  not  sufficient  to  permit  the  use  of  Illinois  coal  alone, 
it  is  sometimes  possible  to  use  one-third  to  one-half  Illinois  coal 
and  in  this  way  decrease  the  cost  of  gas  in  the  holder. 

Advantage  of  Mixing  the  Coals 

The  coals  may  be  charged  separately  into  individual  retorts 
or  may  be  mixed  before  charging.  The  last  method  is  preferable 
as  it  allows  more  uniform  operation  and  gives  better  coke.  When 
the  coals  are  mixed,  the  difficulties  of  regulating  conditions  to 
suit  two  different  coals  are  overcome. 

Illinois  coal  requires  more  heat  to  carbonize  properly  than 
many  other  gas  coals,  and  consequently  either  the  temperature  of 
the  retort  should  be  higher  or  a  longer  period  of  carbonization 
should  be  allowed.  When  part  of  the  retorts  are  charged  with 
Illinois  and  part  with  another  coal,  there  is  difficulty  in  regulat- 
ing conditions  to  suit  both  coals.  For  example,  if  the  temperature 
is  adjusted  to  carbonize  the  Kentucky  coal  in  six  hours,  the  Illi- 
nois coal  will  be  unfinished  at  the  end  of  that  time.  If  carboniza- 
tion is  stopped  the  gas  yield  not  only  will  be  low,  but  the  coke  will 
be  of  poor  quality.  On  the  other  hand,  to  permit  the  Illinois  coal 
to  remain  longer  in  the  retorts  than  the  Kentucky  coal  interferes 
with  the  operating  schedule. 

Method  of  Mixing  the  Coals 

Unlike  by-product  coke  oven  practice,  in  retort  gas  manu- 
facturing it  has  not  been  customary  to  mix  coals  before  charging ; 
consequently  at  gas  plants  there  is  usually.no  mixing  equipment. 
In  small  plants  where  the  retorts  are  hand  fired,  a  coal  crusher 
is  almost  the  only  equipment  required.  The  coals  can  be  mixed 
when  they  are  shoveled  into  the  coal  car  which  hauls  them  to  the 
retorts,  by  taking  alternate  shovelfuls  of  each  kind.  The  coals 
should  be  stored  so  that  each  kind  can  be  loaded  into  the  car  with- 
out changing  its  position.  They  are  re-handled  enough  to  mix 
them  when  they  are  charged  into  the  retorts.  All  the  coal  should 
be  crushed  to  a  maximum  size  of  2  inches,  so  that  non-fusing 
layers  in  Illinois  coal  will  be  mixed  with  the  fusing. 

In  plants  where  the  coal  is  handled  and  the  charging  is  done 
by  machinery,  extra  equipment  usually  will  be  required.  In  some 
cases  the  equipment  in  use  might  be  adapted  to  do  the  work  by 
slight  changes.  No  general  method  can  be  given,  as  most  plants 
are  arranged  differently,  and  mixing  is  a  separate  problem  at 


24  CARBONIZATION   OF  ILLINOIS   COAL 

each.  The  mixing  should  be  done  preferably  before  the  coals  are 
put  into  the  charging  bins,  as  merely  putting  two  kinds  of  coal 
into  the  larry.  would  not  mix  them.  A  good  time  for  mixing  is 
during  crushing.  This  could  be  done  by  having  an  unloading 
hopper  for  each  kind  of  coal  and  a  conveyor  from  each  hopper  to 
the  crusher.  The  desired  amounts  of  each  coal  for  the  mixture 
could  then  be  supplied  to  the  crusher,  and  the  coals  would  mix 
while  being  crushed  and  conveyed  to  the  charging  bins. 


PUBLICATIONS  OF 

ILLINOIS  GOAL  MINING 
INVESTIGATIONS 


ILLINOIS  STATE  GEOLOGICAL  SURVEY  DIVISION 
URBANA,  ILLINOIS 

Bulletin  1.  Preliminary  Report  on  Organization  and  Method  of  Investi- 
gations, 1913. 

Bulletin    3.     Chemical  Study  of  Illinois  Coals,  by  S.  W.  Parr,  1916. 

Bulletin  10.     Coal  Resources  of  District  I  (Longwall),  by  G.  H.  Cady,  1915. 

Bulletin  11.     Coal  Resources  of  District  VII,  by  Fred  H.  Kay,  1915. 

Bulletin  14.  Coal  Resources  of  District  VIII  (Danville),  by  Fred  H.  Kay 
and  K.  D.  White,  1915. 

Bulletin  15.     Coal  Resources  of  District  VI,  by  G.  H.  Cady,  1916. 

Bulletin  16.  Coal  Resources  of  District  II  (Jackson  Co.),  by  G.  H.  Cady, 
1917. 

Bulletin  17.  Surface  Subsidence  in  Illinois  Resulting  from  Coal  Mining, 
by  Lewis  E.  Young,  1916. 

Bulletin  18.  Tests  on  clay  materials  available  in  Illinois  coal  mines,  by 
R.  T.  Stull  and  R.  K.  Hursh,  1947. 

Bulletin  20.  Carbonization  of  Illinois  coals  in  inclined  gas  retorts,  by  F.  K. 
Ovitz,  1918. 


Bulletin  2. 

Bulletin  4. 

Bulletin  5. 

Bulletin  6. 

Bulletin  7. 

Bulletin  8. 

Bulletin  9. 

Bulletin  12. 

Bulletin  13. 

Bulletin  91. 


ENGINEERING  EXPERIMENT  STATION 
URBANA,  ILLINOIS 

Coal  Mining  Practice  in  District  VIII  (Danville),  by  S.  0. 
Andros,  1913. 

Coal  Mining  Practice  in  District  VII,  by  S.  0.  Andros,  1914. 

Coal  Mining  Practice  in  District  I  (Longwall),  by  S.  O.  An- 
dros, 1914. 

Coal  Mining  Practice  in  District  V,  by  S.  0.  Andros,  1914. 

Coal  Mining  Practice  in  District  II,  by  S.  0.  Andros,  1914. 

Coal  Mining  Practice  in  District  VI,  by  S.  O.  Andros,  1914. 

Coal  Mining  Practice  in  District  III,  by  S.  O.  Andros,  1915. 

Coal  Mining  Practice  in  District  IV,  by  S.  0.  Andros,  1915. 

Coal  Mining  in  Illinois,  by  S.  O.  Andros,  1915.  (Complete 
resume  of  all  the  district  reports.) 

Subsidence  Resulting  from  Mining,  by  L.  E.  Young  and  H.  H. 
Stoek,  1916. 


Bulletin    72. 

Bulletin  83. 
Bulletin  99. 
Bulletin  102. 

Bulletin  137. 

Bulletin  138. 


U.  S.  BUREAU  OF  MINES 
WASHINGTON,  D.  C. 

Occurrence   of   Explosive  Gases  in   Coal   Mines,   by   N.   H. 

Darton,  1915. 
The  Humidity  of  Mine  Air,  by  R.  Y.  Williams,  1914. 
Mine  Ventilation  Stoppings,  by  R.  Y.  Williams,  1915. 
The  Inflammability  of  Illinois  Coal  Dusts,  by  J.  K.  Clement 

and  L.  A.  Scholl,  Jr.,  1916. 
Use  of  permissible  explosives  in  the  coal  mines  of  Illinois,  by 

J.  R.  Fleming  and  J.  W.  Rosier,  1917. 
Coking  of  Illinois  coals,  by  F.  K.  Ovitz,  1917. 


